The present invention relates generally to fasteners and more particularly to an improved bearing surface for transmitting torque from a tool to the fastener.
Fasteners are used in numerous applications to attach various components together. Typically, a fastener has at least a threaded portion and one or more bearing surfaces attached thereto. The bearing surfaces are designed to receive torque from a tool, such as a socket or wrench, which is used to tighten or loosen the fastener. In a conventional fastener, such as a nut, the fastener may have internal threads and six bearing surfaces oriented in a hexagon shape around the internal threads. However, other fasteners may have external threads, such as bolts and screws. Fasteners may also have a different number of bearing surfaces as desired.
A common problem that conventional fasteners suffer from is undesirable wear on the corners between adjacent bearing surfaces. This typically occurs because the torque forces applied by the tool become concentrated on the corners of the bearing surfaces. As a result, the corners of the bearing surfaces can become severely deformed by the tool. Deformation of the corners of the bearing surfaces can cause numerous problems. For example, one problem that can occur due to deformation of the corners is premature corrosion of the fastener. This is a common problem because many fasteners are treated with a protective coating to prevent corrosion. However, when the corners become deformed, the protective coating can crack and expose untreated portions of the fastener to exterior moisture. Because many fasteners are visible to individuals, corrosion is especially undesirable because it lowers the aesthetic appeal of the fastener and the equipment the fastener is attached to. In addition, a large buildup of corrosion can make it difficult to fit a torque tool onto the fastener. Substantial corrosion over time can also weaken the strength of the fastener.
Severe deformation of the corners can also interfere with the fit between the torque tool and the fastener in several ways. For example, in some cases, the corners of the bearing surfaces can become so severely rounded that the torque tool is no longer able to adequately engage the bearing surfaces of the fastener and may freely rotate around the fastener without transmitting torque to the threaded portion of the fastener. Deformation of the corners of the bearing surfaces can also cause interference between the fastener and the torque tool. In severe cases, the torque tool may become locked to the fastener and become difficult to remove from the fastener. Similarly, it may be difficult or impossible to fit the torque tool onto the fastener due to severe deformation of the corners of the bearing surfaces. This can be a particular problem for fasteners that utilize a cap. Capped fasteners are typically provided with a decorative metal cap made from stainless steel or other corrosion resistant materials. However, one problem with capped fasteners is that the material of the cap is squeezed between the torque tool and the bearing surfaces of the fastener. As a result, the cap material can swell in size relative to the fastener body and cause interference with the torque tool. In severe cases, the cap material may also fracture.
Accordingly, the inventor believes it would be desirable to provide an improved fastener.